Under option

25 April 2008

More often than not no two lifting jobs are the same and crane users are presented with a challenge unlike any they have faced before. Standard, modular and custom-tailored below the hook equipment gives the range of options to overcome such challenges.

Netherlands-based Unitex Group has developed a range of heavy lifting slings made from polyethylene fibre from DSM Dyneema. These round slings are designed to lift heavy loads weighing up to several hundred tonnes and are at work for Mammoet Van Oord in the Irish Sea. Mammoet Van Oord is using the slings on board its jack up installation barge, Jumping Jack, to place 240 tonne monopiles as part of the foundations required for the installation of wind turbines in the Burbo offshore wind farm project off the coast of Liverpool, UK.

“This new type of lightweight lifting sling performs similarly to steel wire and allows for precise lifting jobs,” said Mammoet Van Ord project manager, Jan Kranenburg. “At the same time, these slings increase the safety of workers on board our vessel. We are happy that Unitex and DSM Dyneema have teamed up to offer this improved type of sling to the market.”

The manufacturer claims that the use of Dyneema fibre in the Unitex lifting slings provides important advantages over traditional equipment. The lightweight fibre enables the manufacture of slings that are lower in weight compared to similar steel-wire based equipment. The lighter weight makes the handling of slings easier, especially in rough seas, and helps prevent back injuries, which are caused most frequently by manual handling of the much heavier steel-wire slings. Wire also carries a high risk of worker injury because loose threads can act like fishhooks and inflict cuts to hands or arms and, Unitex claims, that this kind of injury does not happen when fibre is used instead of traditional wire.

Steel wire can also scratch the coating that provides important corrosion resistance to the monopiles. Slings made from Dyneema help prevent damage to these components, Unitex says.

The company has also launched a range of Dyneema protection sleeves designed to help prevent early wear of polyester-based lifting slings and round slings. Targeted fields of application are transport, construction and industrial areas and include protection for lifting steel plates, marble and concrete.

Spreading the load

Mammoet employed one of the largest heavy lift spreader beams ever used in Australia on the construction of the Phase V LNG Expansion at the Woodside operated North West Shelf Venture, Western Australia. The 26 m long spreader, designed and manufactured by UK-based Modulift, is for loads weighing between 350 and 500 tonnes.

The North Western Shelf Venture is based on the west coast of Australia, at the Burrup Peninsula near Karratha, 1,200 km north of Perth. Commissioned in 1984, the operation has four LNG trains and a capacity of 11.9 million tonnes of LNG a year. On completion, the fifth train will expand this capacity to 16.3 million tonnes a year.

Earlier this year a modular spreader system proved its worth when four Pelamis P-750 wave power machines (manufactured by Camcal) were lifted from the dockside on the Isle of Lewis, off the off the Scottish coast, aboard offshore contractor A2Sea's M/V Sea Power. A Modulift spreader system was used to load the machines in Scotland and then unload them at their destination off the coast of Portugal.

“The P-750 sections vary in length, so we needed the ability to reconfigure the spreader to lengths of 15 and 18 m long. The Modulift system made this easy and helped us to save a lot of time and effort during the lifting process. The nature of Modulift means that we are also able to use the same spreader system for future wind turbine transportation jobs, making it a very cost effective tool.” explains Johnny Lykke, A2Sea technical director.

“The final solution for the lifts consisted of one Modulift spreader set as opposed to a separate spreader for each task. The modular components are used to quickly and efficiently build each different spreader configuration as required for each lift. Additionally, the modular capability will enable this spreader to be re-configured for other applications,” said Modulift director Nick Latham. “Unlike traditional spreaders Modulift doesn't need heavy engineering work to be modified for different lifts.”

Away from custom designed equipment, a range of new standard products is available. One is the Super Bar, a patent-pending spreader from Sunshine of Central Florida, US. The spreader was designed by Trentis Durden, owner of Sunshine of Central Florida. Durden has been a crane owner and operator for almost 30 years. Durden saw the need for a new spreader and has spent the last three years developing the Super Bar.

The 125 ton (113 tonne) capacity bar is available in three sizes and its main selling point is its quick rig spacing time, the manufacturer says. Sunshine says that rig spacing can be changed in less than four minutes and that the Super Bar will “pay for itself in six months” as a result of reduced time and labour costs.

Gunnebo has launched the third generation of its GrabiQ range of lifting chains. Among the new products is the FlexiLeg chain sling, which is made from standard GrabiQ components, allowing the user to select a different number of legs and different end fittings from the existing GrabiQ range. The sling has one master link and a combination of three leg units. Five legs are attached to these units allowing various configurations to suit the required lifting job.

According to the manufacturer, traditional slings are configured with ten legs and the FlexiLeg offers not only a reduction in weight but an advantage to users wanting to alternate configurations quickly on site. Users who would benefit from this time saving, Gunnebo says, are mobile and lorry mounted cranes where lifting requirements change frequently.

Supplied with the FlexiLeg is the MidGrab Shortener which can be positioned anywhere along the sling leg to save time instead of changing the actual length of the sling.•

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